Biliary atresia and the other childhood cholestatic liver diseases are significant causes of chronic liver disease in children, and the leading causes for liver transplantation in pediatrics. The initial funding periods for the proceeding consortiums leading to Childhood Liver Disease Research Network (ChiLDReN) have resulted in unprecedented collections of well phenotyped subjects and banked data and biological specimens. Although ongoing recruitment of subjects with these rare conditions is needed to allow full attainment of many of the individual study Aims, the collection of subjects, data, and biospecimens is now sufficient to support meaningful investigation into the pathogenesis of these diseases and inform the investigation of novel therapies. This next funding period will continue and expand the currently ongoing research of natural history, genetics, and treatment, by continuing to completion the ongoing studies. Furthermore, new therapies will be trialed in the hopes of improving the care that can be provided to children afflicted with these diseases. Usage of the subject data, biospecimens, and engaged subject populations and their families for advancement of knowledge of these diseases and treatment of affected children will also be a priority for this coming funding period. The Seattle Clinical Center has the experience, expertise, and proven track record to continue participation in ChiLDReN, and has the expected patients over time to support the new consortium trials. Dr. Murray and her Clinical Center team has also proposed a study of bleeding risk and platelet function in Alagille syndrome subjects in comparison to subjects with alpha-1-antitrypsin deficiency and progressive familial intrahepatic cholestasis, that will fill a gap in our knowledge about this condition and significantly impact children with Alagille. This study will use a Pediatric Bleeding Questionnaire to assess bleeding risk in these children, and then analyze their platelet function utilizing the Platelet Functional Analyzer-100 and thromboelastography. The results from analysis of these ChiLDReN subjects will be evaluated in conjunction with collected consortium data on these subjects to verify that children with Alagille syndrome have an increased bleeding risk unique to their syndrome and that this is in part due to platelet dysfunction.